Here they are again....
1871
Halifax RG10/4399 Folio 14 Pages 21/22Susanna Wadsworth Head Widow 51 Yorkshire Hull
John do Son U 27 Warehouseman at Spirit Vaults Yorkshire Hull
Jessie do Daur U 24 Worsted Weaver Yorkshire Hull
William do Son U 22 Overlooker of Worsted Spinning Yorkshire Hull
James do Son 20 Overlooker of Worsted Spinning Yorkshire Hull
13 Fitzwilliam Street, Halifax
From the 1851 census entry through to this one, it looks like this John was the son of John the Wood Turner. If that is the case, then it must have been a different John Dunn who married Jane Bastow Holmes in 1868.
It seems to me as if the Baptism document which you have refers to this John Dunn but the Marriage document refers to another one.
Sorry that this is not helping you in the way that you want, but (sticking my neck out

) there seems to me to be something inconsistent in your original information.
It might be advisable to start again from the facts which you know to be absolutely definite and work (either backwards or forwards) from there.
The last few sentences should now almost guarantee that someone else will come along and "shoot me down in flames" by finding the evidence to confirm all that you have said

I, like you, will be very interested to see it
DS